The invention involves a tampon printing machine having at least one engraved printing plate, an inking device that inks a gravure engraving with printing ink and a printing pad that lifts the ink out of the engraving and transfers it to an object that is to be printed.
Many tampon printing machines of this type are known in the prior art. In such a printing machine, the printing plate is inked by an inking device, which can be constructed as a closed system or as an open system. After this inking operation, the image to be printed is filled with printing ink which is lifted out using a printing pad, which, for example, can be made of silicone. The ink that adheres to the printing pad is then transferred via the printing pad to an object to be printed. Tampon printing machines of this type can be optimally integrated into production lines, so that products to be printed can be printed immediately after manufacturing or assembly.
From time to time, there is the need to print the same product with different labels or different products with their correspondingly different labels. In order to be able to make available the respective necessary printing images in as short a time as possible, it has been proposed in German patent DE 40 27 587 C1 to construct a printing plate as a foil printing plate and to arrange several images on the printing plate. In this way, by making available respective images that are needed, which is accomplished by shifting the printing plate, the corresponding objects can be provided with the desired prints.
An object of the invention is to make available a tampon printing machine which is more flexible, in particular one that can be rapidly adapted to changing requirements relative to printing images.
According to principles of this invention for achieving this object, a tampon printing machine of the type mentioned in the opening paragraph includes a laser engraving device connected in-line before an inking device, with which, on the one hand, an engraving can be engraved into a printing plate, and with which, on the other hand, an object to be printed or a printed object, or another object, can be engraved, and a transport device is further included with which the printing plate can be transported from the laser engraving device into an area of the inking device.
A tampon printing machine of the invention is provided with a laser engraving device which gives the printing plate an appropriate engraving prior to an inking of the printing plate. This can be done immediately prior to the inking. After the image is engraved, the printing plate is then transported by a suitable conveyor device from the laser engraving device into an area of the inking device so that the image can be inked. The image is thus engraved into the printing plate by the laser engraving device only shortly prior to the inking operation. In this way, the tampon printing machine can be adapted in a relatively simple and fast manner to different objects to be printed or to different images.
Using the laser engraving device, however, the object that is to be printed or which is already printed can also be engraved, when the need arises. This has the substantial advantage that for preparation of the object to be printed, that is for surface roughing or the like into which the printing ink is subsequently placed, a separate laser station is not necessary. Furthermore, the printed workpiece can be subsequently handled in the same machine, for example, it can be provided with labels or inscriptions. A printing press of the invention additionally creates the possibility of only lasering other objects, which are not to be printed. Objects to be printed can be printed parallel with the lasering.
Advantageously, the position of the laser engraving device relative to the printing pad can be predetermined. In particular, an orientation mark can also be engraved with the laser engraving device, by which the printing plate, for example, can be oriented relative to the inking device and/or the printing tampon by a sensor. The laser engraving device can be completely integrated into the tampon printing machine; however, it is also conceivable that the laser engraving device can be constructed as a separate module that is attachable to the tampon printing machine.
Advantageously, the laser engraving device has a YAG-laser or a CO2-laser. Using these lasers, all laser-capable material can be engraved. In particular, these materials include plastic printing plates and metal foil printing plates.
According to a preferred embodiment, the printing plate is a band printing plate, which is transportable from the laser engraving device in a direction toward the inking device. In this regard, the band printing plate can be unwound from a supply roll and after its use, wound up onto another roll. The band printing plate is thusly pulled a predetermined distance from the supply roll, so that a new image can be lasered onto it. However, it is also conceivable that the band printing plate is drawn off to a greater or lesser distance from the supply roll, depending on the size of the image.
In a preferred embodiment, the laser engraving device and the inking device are arranged between the two rolls. In another embodiment the two rolls are arranged on one side of the machine, in particular on the side that has the laser engraving device. In this way, the possibility is created that the tampon printing machine can be mounted or built both parallel to as well as perpendicularly to a transport direction of a production line.
Another embodiment provides that a printing plate, which is cut to size, can be removed from a stack of printing plates. Non-inscribed printing plates are first located in this stack of printing plates, which are supplied to the laser engraving device so that they can be given the corresponding images. After an engraving, a printing plate is fed to the inking device, so that its image can be inked with printing ink. After use, this printing plate is either sent to a storage area or to a disposal device.
Preferably, a polyester printing plate is used, which, in particular, has a coat of enamel that can be engraved by a laser. Printing plates of this type can be engraved without the edges fraying or the material warping, which would prevent clean wiping by a doctor blade.
Advantageously, the inking device has a drive for an ink fountain, which can be moved in a longitudinal direction or perpendicular direction relative to the transport direction of the printing plate.
Advantageously, the ink fountain can be moved away from the laser engraving device after the inking operation. In this way, it is ensured that not yet used sections of the band-type printing plate are not xe2x80x9cdirtiedxe2x80x9d with printing ink, which could possibly negatively influence a laser operation or an engraving. The ink fountain will thus only be moved back and forth to and from an image to be inked, in a direction of images already inked.
A further embodiment provides that the laser engraving device can be connected to a computer system. Via this computer system, the data for a new image can be entered, that is a customer can either enter the data for the image into the computer system himself, or he can make the data available via a suitable storage medium. In addition, the data for different images can be stored in the computer system, and if necessary, called up in a very short time. Also, data for the engraving of the work pieces and for the printing operation itself can also be entered.
The printing machine of the invention is optimally suited for the purpose of carrying out xe2x80x9cjust-in-timexe2x80x9d printing operations, without having to convert or re-equip the printing machine to do it. In addition, the tampon printing machine is highly flexible and has a high level of integration into the most diverse production lines.
In a further embodiment it is provided that the laser engraving device is constructed for the engraving of printing plates of many tampon printing machines. In this way, an engraving center for printing plates is created which can be applied for various tampon printing machines. The laser engraving device is thus optimally used.
In one embodiment of the tampon printing machine, it is provided that the laser engraving device is set in bearings in one or more carriages, especially so that it can be moved spatially. Preferably, the laser engraving device can also be pivoted in three directions. The laser engraving device can in this way be moved into a laser region for the printing plates and into a laser region for objects. The laser engraving device can in this way be used for engraving objects immediately after their printing plates have been engraved, without any alterations being necessary for this. The tampon printing machine is thus also suitable for small series production.
Preferably, the carriage can be moved into a conveyor area of a transport system for work pieces, for example, a rotary table, a linear conveyor belt, a two-high conveyor belt, or a discontinuous belt. The objects can thus also be brought, in a relatively simple way, during a working cycle, into the working area of the laser engraving device.